Analysis of cold rolled steels of different reduction ratio using the magnetic Barkhausen noise technique

Magnetic Barkhausen Noise (MBN) was used to evaluate the magnetic behaviour of nuclear reactor pressure vessel steel specimens cold rolled to reductio n ratios between 0% and 60%. Measurements performed at increasing reduction ratios revealed variations in the angular dependence of a parameter termed 'MBNenergy', concurrent with modifications in the shape of the pulse heigh t distribution curves. The angular preference of MBNenergy present prior to cold rolling was destroyed at intermediate reduction ratios (approximate t o 25%), and restored with further reduction (approximate to 40%). Along the rolling direction, the number of large voltage pulses was reduced at reduc tion ratios of approximate to 25%, increasing again at approximate to 60% r eduction ratio. Results were attributed to competing effects between crysta llographic texture, microscopic and macroscopic residual stresses. (C) 2001 Kluwer Academic Publishers.